<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <script src="../react18/react.development.js"></script>
  <script src="../react18/react-dom.development.js"></script>
  <script src="../react18/babel.min.js"></script>
  <script src="../react18/prop-types.js"></script>
</head>

<body>
  <div id="app"></div>
  <script type="text/babel">
    /* class App extends React.Component{
            state = {
        opacity : 1
      }

      render(){ 
        let {opacity} = this.state;
        return (
          <div>
            <h1 style={{opacity}}>React真难啊</h1>
            <button onClick={this.handle}>不学了 我学vue去了</button>  
          </div>
        )
      }

      componentDidMount(){
        let {opacity} = this.state;
        this.timer = setInterval(()=>{
          opacity -= 0.1;
          if(opacity <= 0){
            opacity =1
          }
          this.setState({opacity})
        },100)
      }

      componentwillUnmount(){
        clearInterval(this.timer)
      }

      handle = () => {
        root.unmount();
      }
    }

    const root = ReactDOM.createRoot(document.getElementById('app'));
    root.render(<App/>) */



    /* class App extends React.Component{
      state = {
        opacity : 1
      }

      render(){
        let {opacity} = this.state;
        return(
          <div>
            <h1 style={{opacity}}>React真难啊</h1>
            <button onClick={this.handle}>不学了 我学vue去了</button>
          </div>
        )
      }

      handle = () => {
        root.unmount();
      }

      //组件挂载完成执行,主要用来初始化操作:比如ajax请求,定时器,订阅等
      componentDidMount(){
        let {opacity} = this.state;
        this.timer = setInterval(()=>{
          opacity -= 0.05;
          if(opacity <= 0){
            opacity =1
          }
          this.setState({opacity})
        },100)
      }

      //组件将要挂载执行
      componentWillMount(){
        clearInterval(this.timer)
      }

    }

    const root = ReactDOM.createRoot(document.getElementById('app'));
    root.render(<App/>) */




    class App extends React.Component{
      state = {
        opacity : 1
      }

      render(){
        const {opacity} = this.state;
        return(
          <div>
           <h1 style = {{opacity}}>找不到工作怎末办</h1>
           <button onClick = {this.deleteApp}>不活了</button>
          </div>
        )
      }


      //只要opacity改变组件就会g挂载就会一直创建定时器  //所以在挂载之前要清除上一次的定时器
      componentDidMount(){
        console.log("组件挂载完成了");
        console.log("重新设置了一个定时器");

        let {opacity} = this.state;
        this.times = setInterval(()=>{
          opacity -= 0.05;
          if(opacity < 0){
            opacity = 1
          }
          this.setState({opacity:opacity})
        },100)
      }

      //在挂载之把定时器清除
      componentWillMount(){
        console.log("组件将要被挂载");
        console.log("上次的定时器被清除了");
        
        clearInterval(this.timer)
      }


      deleteApp = () =>{
        root.unmount()
      }
    }

    const root = ReactDOM.createRoot(document.getElementById('app'))
    root.render(<App/>)







  </script>
</body>

</html>